Chapter 13: Meiosis

Question 1

Somatic Cells

Answer 1

All cells other than sex cells

Question 2

Gametes

Answer 2

Sex cells ( sperm or egg)

Question 3

Autosomes

Answer 3

The chromosomes which code for information other that gender (22 pairs)

Question 4

Sex Chromosomes

Answer 4

The chromosomes which code for information including gender. The 23rd pair X or Y

Question 5

Homologous Chromosomes

Answer 5

The pair of chromosomes which code for the same trait

Humans have a set of 23 homologous chromosomes

Question 6

Karyotype

Answer 6

It identifies the number and types of chromosomes present in a species

Question 7

Diploid

Answer 7

The have two Homo logs of each chromosome

They 2 alleles of each gene

Humans are this

A full set of chromosomes. A pair of each homologous chromosome

Question 8

Haploid

Answer 8

They have only one of each type of chromosomes

They have just one allele of each gene
1/2 the number of chromosomes as a parent cell. 1 of each homologous pair.

Question 9

What do each species have ?

Answer 9

Haploid number (n)
— indicates the number of distinct types of chromosomes present
—- Sex chromosomes count as a single type
—- In humans , n , is 23

Question 10

What does the cell’s ploidy indicates? , 2n, n, 3n

Answer 10

The number of complete chromosomes set it contains

Question 11

What do diploids cells have?

Answer 11

A paternal chromosome that came from the father

A maternal chromosome that came from the mother

Humans are diploids 2n = 46

Question 12

Polyploid

Answer 12

Organisms w/ 3 or more versions of each type of chromosome , 3n 4n etc.

Tetraploidy, Hexaplod, Triploidy

Question 13

Does having more chromosomes make the organism more complicated?

Answer 13

No, the # of chromosomes does not denote biological complexity

Question 14

Meiosis v. Mitosis

Answer 14

Meiosis
-Occurs in 2 stages
- Begin with1 diploid cell & end with 4 haploid cells
-Gametes

Mitosis
-Occurs in 1 stage
-Begins w/ 1 diploid cell & end w/ 2 diploid cells
- Somatic Cells

Question 15

Reductional Division

Answer 15

When the number of diploids is reduced to a haploid.

Result of Meiosis I: In 2 haploid daughter cells with replicated chromosomes

Question 16

What happens during meiosis II ?

Answer 16

Sister chromatids separate.

Question 17

What is the 1 division of meiosis?

Answer 17

Separation of homologous pairs

2n –> 1n

Question 18

What is the 2nd division of meiosis?

Answer 18

Separation of sister chromatids

1n –> 1n

Question 19

What is crossing over?

Answer 19

During Prophase I, homologous pairs swap pieces of chromosome, sister chromatids intertwine.

Question 20

Random Fertilization

Answer 20

Any 2 parents will produce a zygote w/ over 70 trillion diploid combos

Question 21

Sources of genetic variability

Answer 21

• independent assortment
  homologous chromosomes in Meiosis I
• crossing over
  b/tw homologous chromosomes in prophase I
• random fertilization
  random ovum fertilized by a random sperm

Question 22

Nondisjunction

Answer 22

the failure of the chromosomes to separate which produces daughter cells w/ abnormal numbers of chromosomes.

Question 23

Trisomy 21

Answer 23

Down Syndrome
- delayed mental and social skills
- decreased muscle tone at birth
- asymmetrical or odd-shaped skull
- small skull
- small mouth w/ protruding tongue
- broad short hands
- increased risk of developing Leukemia and Alzheimer’s later in life.